Controllable commutation converter valve active support test circuit, method and device

Abstract

The invention provides a controllable commutation converter valve active support test circuit, method and device. According to the active support test circuit for the controllable commutation converter valve, the resonant capacitor in the multi-wave resonant current source is charged through the charging equipment, periodic energy compensation can be effectively performed on the resonant capacitor, the steady-state power supply and the multi-wave resonant current source provide voltage and current stress required by a test for the sample valve, the sample valve is tested, and the test efficiency is improved. The device effectively verifies the stress of a power electronic device and the design rationality of the converter valve, truly simulates the supporting capability of the converter valve on the system when the AC system breaks down, and can effectively verify the voltage, current and thermal stress borne by each component of the converter valve under the actual working condition. And the test requirements of active support required by different direct-current power transmission system projects can be met.

Description

Technical Field

[0001] This invention relates to the field of DC power transmission technology, specifically to a controllable commutation converter valve active support test circuit, method, and device. Background Technology

[0002] In most regions, HVDC transmission systems employ multi-feed DC systems at the receiving end, resulting in tight inter-station coupling. Multi-station interlocking can exacerbate commutation failures, posing a greater challenge to the safe and stable operation of the power grid. Therefore, converters with controllable topologies capable of withstanding commutation failures are increasingly becoming a research hotspot. Controllable commutation converter valves, as a novel type of converter equipment, can completely resist commutation failures and are already being used in HVDC transmission projects. They are expected to have even wider applications in future renovation and new construction projects.

[0003] Because DC transmission equipment generally features high voltage, high current, and large capacity, it is difficult to construct a full-load circuit identical to the actual operating conditions in the test environment. Therefore, constructing an equivalent test circuit and conducting tests with intensity comparable to actual operating conditions becomes an inevitable choice. Ultra-high voltage DC transmission systems require controllable commutation valves with second-level active support capabilities, meaning they can continuously and periodically shut off large currents.

[0004] To verify the resilience of the controllable topology converter against commutation failure caused by AC faults and its active support capability, it is necessary to test the controllable turn-off capability of the AC fault current flowing through the converter valve. This ensures that the converter has the ability to complete forced commutation by continuously turning off the fault current within seconds. Therefore, active support testing is an important test method to ensure the design and manufacturing level of the UHV controllable topology converter and to ensure its ability to resist commutation failure faults. This test not only needs to verify the voltage, current, and thermal stress borne by each component of the converter valve during forced commutation, the commutation time of the main and auxiliary branches and the bridge arm, and the energy absorption of the surge arrester, but also needs to prove that the components can withstand the transient stress of high di / dt and du / dt when the turn-off current is applied.

[0005] The existing test scheme involves charging the resonant capacitor before the test and not replenishing it during the test. After the capacitor discharges to the test valve each cycle, the remaining voltage cannot support the periodic fault current shutdown test for a long time, and cannot meet the requirements of the second-level active support test. Summary of the Invention

[0006] To address the problem in existing technologies that the resonant capacitor no longer provides energy during testing, and the remaining voltage after the test valve discharges cannot sustain the fault current shutdown test for an extended period, this invention provides a controllable commutation valve active support test circuit, method, and apparatus.

[0007] In a first aspect, the present invention provides a controllable commutation valve active support test circuit, the test circuit comprising: a steady-state power supply, a multi-wave resonant current source, and a charging device; The steady-state power supply and the multi-wave resonant current source are respectively connected in parallel with the external test valve. The charging device is connected to the multi-wave resonant current source. The test valve is a controllable commutation valve or a controllable commutation valve section. The steady-state power supply is used to provide voltage and current to simulate the steady-state operation of the test valve; The charging device is used to charge the resonant capacitor in the multi-wave resonant current source; The multi-wave resonant current source is used to output a controllable additional fault current. The controllable additional fault current is superimposed with the current output by the steady-state power supply to form a test fault current that can simulate an AC fault. The test valve is subjected to an active support test by the voltage output by the steady-state power supply and the test fault current.

[0008] Optionally, the test circuit further includes: a control backend; The control backend is connected to the steady-state power supply, the multi-wave resonant current source, the charging device, and the sample valve, respectively. The control backend is used to control the output voltage and current of the steady-state power supply and the output controllable additional fault current of the multi-wave resonant current source according to the preset test fault current control sequence, so as to form a test fault current that can simulate AC faults; it is also used to control the charging device to charge the resonant capacitor in the multi-wave resonant current source according to the preset switching device control sequence.

[0009] Optionally, the charging device includes: a charging power supply and a plurality of switching devices; The charging power supply is connected to the multi-wave resonant current source through the plurality of switching devices; The control backend is connected to the plurality of switching devices; The control backend is specifically used to control the multiple switching devices to be turned on according to the preset switching device control sequence, so that the charging power supply charges the resonant capacitor in the multi-wave resonant current source.

[0010] Optionally, the charging power supply is a DC power supply, and the plurality of switching devices are all fully controlled power electronic devices.

[0011] Optionally, the multi-wave resonant current source includes multiple resonant branches connected in parallel; Each resonant branch is connected to the first terminal of its corresponding switching device, and the second terminal of each switching device is connected to the charging power supply. The control backend is connected to the plurality of resonant branches; The control backend is specifically used to control the target resonant branch among the multiple resonant branches to output a controllable additional fault current to the test valve based on a preset test fault current control timing sequence; and to control the switching device corresponding to at least one resonant branch among the remaining resonant branches to be turned on according to the preset switching device control timing sequence, so that the charging power supply charges the resonant capacitor in the at least one resonant branch.

[0012] Optionally, each resonant branch includes: a reactor, an auxiliary valve, and a resonant capacitor, wherein the auxiliary valve is a controllable power electronic device; The first end of the reactor is connected to the positive terminal of the resonant capacitor through the auxiliary valve; The second terminal of the reactor is connected to the input terminal of the test valve and the positive terminal of the steady-state power supply. The positive terminal of the resonant capacitor is also connected to the second terminal of the switching device corresponding to the resonant branch where the resonant capacitor is located. The output terminal of the test valve, the negative terminal of the steady-state power supply, and the negative terminal of the resonant capacitor are grounded.

[0013] Optionally, the test valve includes: a current-shutdown branch and an auxiliary commutation branch connected in parallel, wherein the current-shutdown branch includes a plurality of first branches connected in parallel, and the auxiliary commutation branch includes a plurality of second branches connected in parallel. The control backend is connected to each of the plurality of first branches; The control backend is specifically used to control one of the multiple first branches to be turned on or off in sequence according to the preset test fault current control timing.

[0014] A second aspect of the present invention also provides a test method for active support of a controllable commutation valve, applicable to the test circuit described in the first aspect of the present invention, the method comprising: The steady-state power supply provides the voltage and current to simulate the steady-state operation of the external test valve; The charging device is controlled to charge the resonant capacitor in the multi-wave resonant current source. The multi-wave resonant current source is controlled based on the resonant capacitor and reactor to output a controllable additional fault current. The controllable additional fault current is superimposed with the current output by the steady-state power supply to form a test fault current that can simulate AC faults. The test valve is subjected to active support test by the voltage output by the steady-state power supply and the test fault current.

[0015] Optionally, the multi-wave resonant current source includes multiple resonant branches connected in parallel; The control of the charging device to charge the resonant capacitor in the multi-wave resonant current source includes: Based on the preset test fault current control timing sequence, the target resonant branch in the plurality of resonant branches is controlled to output a controllable additional fault current to the test valve; according to the preset switching device control timing sequence, the switching device corresponding to at least one resonant branch in the remaining resonant branches is controlled to be turned on, so that the charging power supply charges the resonant capacitor in the at least one resonant branch.

[0016] A third aspect of the present invention also provides a test device for active support of a controllable commutation valve, the test device comprising: the test circuit described in the first aspect of the present invention.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a controllable commutation converter valve active support test circuit, method, and apparatus. The controllable commutation converter valve active support test circuit charges the resonant capacitor in the multi-wave resonant current source through a charging device, effectively periodically replenishing the resonant capacitor. The steady-state power supply and the multi-wave resonant current source provide the voltage and current stress required for the test on the test valve. The test on the test valve effectively verifies the stress on the power electronic devices and the rationality of the converter valve design. It realistically simulates the converter valve's ability to support the system by continuously shutting off the fault current for seconds when a fault occurs in the AC system. It can effectively verify the voltage, current, and thermal stress borne by each component of the converter valve under actual operating conditions, and can meet the active support test requirements of different DC transmission system projects. Attached Figure Description

[0018] Figure 1 A schematic diagram of an active support test circuit for a controllable commutation valve provided by the present invention; Figure 2 A schematic diagram of an active support test circuit for a controllable commutation valve provided by the present invention; Figure 3 A schematic diagram of an active support test circuit for a controllable commutation valve provided by the present invention; Figure 4 A schematic diagram of a resonant capacitor energy replenishment method provided by the present invention; Figure 5 A schematic diagram of a k-1 group resonant capacitor energy replenishment method provided by the present invention; Figure 6 A resonant capacitor control logic diagram provided by the present invention; Figure 7 A schematic diagram of an active support test circuit for a controllable commutation valve provided by the present invention; Figure 8 A topology diagram of a controllable converter valve provided by the present invention; Figure 9The waveform diagram of the trigger pulse and voltage-current test of the multi-branch VT valve for controllable shutdown test provided by the present invention; Figure 10 The waveform diagram of the trigger pulse and voltage-current test of the multi-branch VT valve for controllable shutdown test provided by the present invention; Figure 11 The waveform diagram of the trigger pulse and voltage-current test of the multi-branch VT valve for controllable shutdown test provided by the present invention. Detailed Implementation

[0019] Example 1: Figure 1 A schematic diagram of an active support test circuit for a controllable commutator valve provided by the present invention is shown below. Figure 1 As shown, the test circuit may include: a steady-state power supply, a multi-wave resonant current source, and a charging device; the steady-state power supply and the multi-wave resonant current source can be connected in parallel with an external test valve, and the charging device can be connected to the multi-wave resonant current source; the test valve can be a controllable commutator valve or a controllable commutator valve section; the steady-state power supply can be used to provide voltage and current simulating the steady-state operation of the test valve; the charging device can be used to charge the resonant capacitor in the multi-wave resonant current source; the multi-wave resonant current source can be used to output a controllable additional fault current, and the controllable additional fault current and the current output by the steady-state power supply can be superimposed to form a test fault current that can simulate an AC fault, and the test valve is subjected to an active support test by the voltage output by the steady-state power supply and the test fault current.

[0020] It should be noted that the output terminal of the charging device is connected to the resonant capacitor of the multi-wave resonant current source. When the charging device and the resonant capacitor of the multi-wave resonant current source form a charging circuit, the resonant capacitor of the multi-wave resonant current source is charged. The multi-wave resonant current source discharges and outputs a controllable additional fault current through the resonant circuit formed by the resonant capacitor and the reactor. The positive terminal of the steady-state power supply and the positive terminal of the multi-wave resonant current source are respectively connected to the input terminal of the external test valve. The negative terminal of the steady-state power supply, the negative terminal of the multi-wave resonant current source, and the output terminal of the external test valve are grounded. The current output by the steady-state power supply and the controllable additional fault current output by the multi-wave resonant current source are superimposed at the input terminal of the test valve to form a test fault current that can simulate AC faults. This allows the test fault current to flow through the test valve, realizing the test fault current required for the active support test of the test valve.

[0021] Optionally, the test circuit may further include: a control backend; the control backend can be connected to the steady-state power supply, the multi-wave resonant current source, the charging device, and the test sample valve, respectively; the control backend can be used to control the output voltage and current of the steady-state power supply and the output controllable additional fault current of the multi-wave resonant current source according to a preset test fault current control sequence, which can be superimposed to form a test fault current that can simulate an AC fault; it is also used to control the charging device to charge the resonant capacitor in the multi-wave resonant current source according to a preset switching device control sequence.

[0022] Optionally, the charging device includes: a charging power supply and multiple switching devices; the charging power supply is connected to the multi-wave resonant current source through the multiple switching devices; the control backend is connected to the multiple switching devices; the control backend is specifically used to control the multiple switching devices to conduct according to the preset switching device control sequence, so that the charging power supply charges the resonant capacitor in the multi-wave resonant current source.

[0023] The charging power supply is a DC power supply, and the multiple switching devices are all fully controlled power electronic devices, such as: IGBT (Insulated-Gate Bipolar Transistor), IGCT (Integrated Gate-Commutated Thyristor), IEGT (Injection Enhanced Gate Transistor), GTO (Gate-Turn-Off Thyristor), or MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), etc. To achieve the goal of supplying C during the experiment... k The power supply for replenishing energy can be a DC / DC device, a supercapacitor, or a rectifier bridge, or other devices that can output DC current.

[0024] It should be noted that the charging device may also include: a DC transformer; the output terminal of the DC transformer is connected to the charging power supply, and the input terminal of the DC transformer is connected to an external DC power supply. Alternatively, the charging device may also include: a rectifier; the output terminal of the rectifier is connected to the charging power supply, and the input terminal of the rectifier is connected to an external AC power supply.

[0025] For example, the core of the second-level active support test lies in providing the resonant capacitor C with power during the test. k This achieves energy replenishment, realizes energy equivalence between the auxiliary commutation branch surge arrester and the bridge arm commutation time. For example... Figure 2As shown, when the charging power source is a DC / DC device, the input terminal of the DC / DC device is connected to an external DC power source via a DC transformer, which can be a DC mains grid. Alternatively, the input terminal of the DC / DC device is connected to an external AC power source via a rectifier, which can be an AC mains grid. Figure 3 As shown, when the charging power source is a supercapacitor, the input terminal of the supercapacitor is connected to an external DC power source.

[0026] Optionally, the multi-wave resonant current source includes multiple resonant branches connected in parallel; each resonant branch is connected to the first terminal of its corresponding switching device, and the second terminal of each switching device is connected to the charging power supply; the control backend is connected to the multiple resonant branches; the control backend is specifically used to control the target resonant branch among the multiple resonant branches to output a controllable additional fault current to the test valve based on a preset test fault current control timing sequence; and to control the switching device corresponding to at least one of the remaining resonant branches to be turned on according to the preset switching device control timing sequence, so that the charging power supply charges the resonant capacitor in the at least one resonant branch.

[0027] For example, there are two ways for the charging device to replenish the energy of k sets of resonant power sources: One method involves replenishing energy to only one group of resonant capacitors per cycle. This means that one group of capacitors discharges to the test valve during the current cycle, while charging one of the remaining k-1 groups of capacitors. The remaining k-2 groups remain inactive. This is based on the preset test fault current control sequence. Figure 4 As shown, where, ft 1 is the trigger pulse of harmonic current source V1. ft 2 is the trigger pulse for harmonic current source V2. ft n harmonic current source V n The trigger pulse, t 11 t 12 t 13 t 21 t 22 t 23 t n1 t n2 t n3 It can be used to determine the first triggering timing of multiple resonant branches in a harmonic current source.

[0028] Another method involves replenishing the energy of k-1 groups of resonant capacitors (k=1,2,…,n) per cycle. That is, in this cycle, one group of capacitors discharges at the test valve, while the remaining k-1 groups of capacitors are charged. The charging time continues until the cycle before the next capacitor action. This is based on the preset test fault current control sequence. Figure 5 As shown, where t 1n1 t 1n2It can be used to determine the conduction timing of the second trigger of multiple resonant branches in a harmonic current source.

[0029] The flowcharts for the two control methods are as follows: Figure 6 As shown, the two control methods differ only in the charging time for each resonant capacitor.

[0030] Optionally, each resonant branch includes: a reactor, an auxiliary valve, and a resonant capacitor, wherein the auxiliary valve is a controllable power electronic device; the first end of the reactor is connected to the positive terminal of the resonant capacitor through the auxiliary valve; the second end of the reactor is connected to the input end of the test valve and the positive terminal of the steady-state power supply; the positive terminal of the resonant capacitor is also connected to the second end of the switching device corresponding to the resonant branch in which the resonant capacitor is located; and the output end of the test valve, the negative terminal of the steady-state power supply, and the negative terminal of the resonant capacitor are grounded.

[0031] For example, Figure 7 The diagram shows a feasible circuit for this test method. The circuit is divided into two parts according to its test function: ① Steady-state power supply – This power supply provides the voltage and current to simulate the steady-state operation of the controllable commutator valve; ② Multi-wave resonant current source – This utilizes a charging device (i.e., charging equipment) to... k (k=1,2,…,n) sets of parallel circuits (i.e., resonant branches) are charged, and each set of capacitors (i.e., resonant capacitors) is charged. C k With reactor L k via auxiliary valve V k Under the corresponding logic timing, a controllable additional fault current is generated in conjunction with the trigger shutdown. This controllable additional fault current is superimposed on the aforementioned basic current to form... k One cycle can simulate the fault current of an AC fault (i.e., the test fault current).

[0032] Optionally, the test valve includes: a current-cut-off branch and an auxiliary commutation branch connected in parallel, the current-cut-off branch including a plurality of first branches connected in parallel, and the auxiliary commutation branch including a plurality of second branches connected in parallel; the control backend is connected to the plurality of first branches respectively; the control backend is specifically used to control one of the plurality of first branches to be turned on or off sequentially according to the preset test fault current control timing sequence.

[0033] For example, such as Figure 8 As shown, the controllable converter valve consists of a + b The branch roads are connected in parallel, among which a ( a =1,2,..., pThe branch is a current-interrupting branch, containing one or more power electronic devices with current-interrupting and forward / reverse voltage blocking capabilities, such as IGBTs, IGCTs, IEGTs, GTOs, or MOSFETs. b ( b =1,2,..., q The branch is an auxiliary commutation branch used to establish the commutation voltage of the converter valve. This branch does not contain power electronic devices.

[0034] The control logic timing of the converter valve VT with controllable turn-off or controllable commutation capability must meet the requirement of interrupting the AC fault current flowing through the bridge arm during simulated bridge arm commutation during the test, establishing the commutation voltage through the turn-off current, and realizing the forced commutation function of the bridge arm. Forced commutation testing, conducted in minimum turn-off angle mode, can be categorized into two methods based on the way the converter valve VT interrupts the fault current: 1) The converter valve VT, containing power electronic devices, is divided into at least two branches, each containing power electronic devices with current-interrupting and forward / reverse voltage blocking capabilities, such as one or more of IGBTs, IGCTs, IEGTs, GTOs, or MOSFETs. First, the steady-state power supply needs to provide the controllable converter valve VT with the voltage and current required for the minimum turn-off angle test. Based on this, the power electronic device in branch 1 is turned on at time t1. Upon receiving a logic timing command from the control backend, the controllable power electronic device in branch 1 turns off at time t2, and the power electronic device in branch 2 turns on, transferring current from branch 1 to branch 2. Subsequently, at time t3, the controllable power electronic device in branch 2 receives a logic timing command from the control backend and turns off, transferring current to the branch without power electronic devices, establishing the VT valve turn-off voltage, and achieving forced commutation. At any time between t1 and t2, a multi-wavelength harmonic current source injects harmonic currents of corresponding wavelengths and widths according to the test requirements. These harmonic currents are superimposed with the current provided by the steady-state power supply to form the fault current required by the converter valve VT. Trigger pulses and voltage / current waveforms of the power electronic components inside the converter valve VT are as follows: Figure 9 As shown.

[0035] 2) The converter valve VT has only one branch containing power electronic devices. This branch must include power electronic devices with current-interrupting and forward / reverse voltage blocking capabilities, such as one or more of IGBTs, IGCTs, IEGTs, GTOs, or MOSFETs. The power electronic devices in the converter valve VT are turned on at time t1 and turned off at time t2 upon receiving a logic timing command from the control backend. The AC fault current is transferred to the branch without power electronic devices, completing forced commutation. A multi-wave harmonic current source injects harmonic current of the appropriate wave and width according to the test requirements at any time between t1 and t2. The harmonic current is superimposed on the current provided by the steady-state power supply to form the fault current required by the converter valve VT. The trigger pulses for the power electronic components inside the converter valve VT are as follows: Figure 10 As shown.

[0036] Selection method of resonant capacitor and reactor inductance value For the equivalent bridge arm commutation time and the energy absorption of the auxiliary branch surge arrester of the test valve, L k Due to limitations in the actual engineering commutation inductance, the actual engineering commutation inductance is set to L. x The test valve is an actual six-pulse valve. Single valve, .

[0037] In addition, the fault current half-wave width of the multi-harmonic current source, and the width of each group of current sources. C can be calculated based on this formula. k Values.

[0038] This invention realistically simulates the continuous second-level interruption of fault current by the converter valve during an AC system failure. It effectively verifies the voltage, current, and thermal stress borne by each component of the converter valve under actual operating conditions, the commutation time of the main and auxiliary branches, the commutation time of the bridge arm, the active support capability of the controllable commutation converter valve, and the transient stresses of high di / dt and du / dt during the shutdown process. The proposed fault current source with multiple sets of parallel charging devices can meet the forced commutation test requirements of different DC transmission system projects, demonstrating good versatility.

[0039] This invention simulates the process of switching off AC fault current, establishing voltage, and commutating the bridge arm of a converter valve, effectively verifying the active support capability of a controllable topology converter valve. The new synthetic test circuit can inject multiple sets of fault currents according to the number of parallel charging devices in the fault current source, and replenish the resonant capacitor through the charging equipment, achieving the second-level active support capability test requirements. This effectively verifies the stress on power electronic devices and the rationality of the converter valve design.

[0040] Example 2: A second aspect of the present invention also provides a test method for active support of a controllable commutation valve, applicable to the test circuit described in the first aspect of the present invention, the method comprising: The steady-state power supply provides the voltage and current to simulate the steady-state operation of the external test valve; The charging device is controlled to charge the resonant capacitor in the multi-wave resonant current source. The multi-wave resonant current source is controlled based on the resonant capacitor and reactor to output a controllable additional fault current. The controllable additional fault current is superimposed with the current output by the steady-state power supply to form a test fault current that can simulate AC faults. The test valve is subjected to active support test by the voltage output by the steady-state power supply and the test fault current.

[0041] Optionally, the multi-wave resonant current source includes multiple resonant branches connected in parallel; The control of the charging device to charge the resonant capacitor in the multi-wave resonant current source includes: Based on the preset test fault current control timing sequence, the target resonant branch in the plurality of resonant branches is controlled to output a controllable additional fault current to the test valve; according to the preset switching device control timing sequence, the switching device corresponding to at least one resonant branch in the remaining resonant branches is controlled to be turned on, so that the charging power supply charges the resonant capacitor in the at least one resonant branch.

[0042] This invention proposes a controllable commutation converter valve active support test circuit and method, employing a synthetic multi-source injection test approach. By using an LC resonant circuit, an adjustable half-wave multi-wave current is injected, which is superimposed on the test current borne by the converter valve itself to form a test current capable of verifying the controllable shut-off function of the converter valve. An energy replenishment circuit is introduced to periodically replenish the energy of capacitor C after its discharge, supporting second-level test capabilities. This test is completed through the timing coordination of the various power electronic devices inside the converter valve test and the timing of the injected current in the resonant circuit, meeting the active support test requirements of ultra-high voltage direct current transmission system projects.

[0043] Example 3: A third aspect of the present invention also provides a test device for active support of a controllable commutation valve, the test device comprising: the test circuit described in the first aspect of the present invention.

[0044] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A controllable commutation valve active support test circuit, characterized in that, The test circuit includes: a steady-state power supply, a multi-wave resonant current source, and a charging device; The steady-state power supply and the multi-wave resonant current source are respectively connected in parallel with the external test valve. The charging device is connected to the multi-wave resonant current source. The test valve is a controllable commutation valve or a controllable commutation valve section. The steady-state power supply is used to provide voltage and current to simulate the steady-state operation of the test valve; The charging device is used to charge the resonant capacitor in the multi-wave resonant current source; The multi-wave resonant current source is used to output a controllable additional fault current. The controllable additional fault current is superimposed with the current output by the steady-state power supply to form a test fault current that can simulate an AC fault. The test valve is subjected to an active support test by the voltage output by the steady-state power supply and the test fault current.

2. The test circuit according to claim 1, characterized in that, The test circuit also includes: a control backend; The control backend is connected to the steady-state power supply, the multi-wave resonant current source, the charging device, and the sample valve, respectively. The control backend is used to control the output voltage and current of the steady-state power supply and the output controllable additional fault current of the multi-wave resonant current source according to the preset test fault current control sequence, so as to form a test fault current that can simulate AC faults; it is also used to control the charging device to charge the resonant capacitor in the multi-wave resonant current source according to the preset switching device control sequence.

3. The test circuit according to claim 2, characterized in that, The charging device includes: a charging power supply and multiple switching devices; The charging power supply is connected to the multi-wave resonant current source through the plurality of switching devices; The control backend is connected to the plurality of switching devices; The control backend is specifically used to control the multiple switching devices to be turned on according to the preset switching device control timing, so that the charging power supply charges the resonant capacitor in the multi-wave resonant current source.

4. The test circuit according to claim 3, characterized in that, The charging power supply is a DC power supply, and the multiple switching devices are all fully controlled power electronic devices.

5. The test circuit according to claim 3, characterized in that, The multi-wave resonant current source includes multiple resonant branches connected in parallel; Each resonant branch is connected to the first terminal of its corresponding switching device, and the second terminal of each switching device is connected to the charging power supply. The control backend is connected to the plurality of resonant branches; The control backend is specifically used to control the target resonant branch among the multiple resonant branches to output a controllable additional fault current to the test valve based on a preset test fault current control timing sequence; and to control the switching device corresponding to at least one resonant branch among the remaining resonant branches to be turned on according to the preset switching device control timing sequence, so that the charging power supply charges the resonant capacitor in the at least one resonant branch.

6. The test circuit according to claim 5, characterized in that, Each resonant branch includes: a reactor, an auxiliary valve, and a resonant capacitor, wherein the auxiliary valve is a controllable power electronic device; The first end of the reactor is connected to the positive terminal of the resonant capacitor through the auxiliary valve; The second terminal of the reactor is connected to the input terminal of the test valve and the positive terminal of the steady-state power supply. The positive terminal of the resonant capacitor is also connected to the second terminal of the switching device corresponding to the resonant branch where the resonant capacitor is located. The output terminal of the test valve, the negative terminal of the steady-state power supply, and the negative terminal of the resonant capacitor are grounded.

7. The test circuit according to any one of claims 2-6, characterized in that, The test valve includes: a current shut-off branch and an auxiliary commutation branch connected in parallel. The current shut-off branch includes a plurality of first branches connected in parallel, and the auxiliary commutation branch includes a plurality of second branches connected in parallel. The control backend is connected to each of the plurality of first branches; The control backend is specifically used to control one of the multiple first branches to be turned on or off in sequence according to the preset test fault current control timing.

8. A test method for active support of a controllable commutation valve, characterized in that, The method, applicable to the test circuit according to any one of claims 1-7, comprises: The steady-state power supply provides the voltage and current to simulate the steady-state operation of the external test valve; The charging device is controlled to charge the resonant capacitor in the multi-wave resonant current source. The multi-wave resonant current source is controlled based on the resonant capacitor and reactor to output a controllable additional fault current. The controllable additional fault current is superimposed with the current output by the steady-state power supply to form a test fault current that can simulate AC faults. The test valve is subjected to active support test by the voltage output by the steady-state power supply and the test fault current.

9. The method according to claim 8, characterized in that, The multi-wave resonant current source includes multiple resonant branches connected in parallel; The control of the charging device to charge the resonant capacitor in the multi-wave resonant current source includes: Based on the preset test fault current control timing sequence, the target resonant branch in the plurality of resonant branches is controlled to output a controllable additional fault current to the test valve. According to the preset switching device control timing, at least one of the switching devices corresponding to the remaining resonant branches is turned on, so that the charging power supply charges the resonant capacitor in the at least one resonant branch.

10. A test device for active support of a controllable commutation valve, characterized in that, The test apparatus includes the test circuit described in any one of claims 1-7.

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